GL establishes a
``working set'' of textures that are resident in texture memory. These textures
can be bound to a texture target much more efficiently than textures that
are not resident.

glAreTexturesResident queries the texture residence status
of the n textures named by the elements of textures. If all the named textures
are resident, glAreTexturesResident returns GL_TRUE, and the contents of
residences are undisturbed. If not all the named textures are resident,
glAreTexturesResident returns GL_FALSE, and detailed status is returned
in the n elements of residences. If an element of residences is GL_TRUE,
then the texture named by the corresponding element of textures is resident.

The residence status of a single bound texture may also be queried by calling
glGetTexParameter with the target argument set to the target to which
the texture is bound, and the pname argument set to GL_TEXTURE_RESIDENT.
This is the only way that the residence status of a default texture can
be queried.